The present invention relates generally to a video communications systems, and more specifically to the conversion of a color television signal in the NTSC (National Television Standard Committee) or PAL (Phase Alternation by Line) system format into a common intermediate format (CIF) standardized by CCITT.
A conventional CIF converter comprises a series of five memories for respectively storing successive five horizontal lines of an NTSC or PAL signal to produce a set of pixel data spaced a horizontal line apart from each other. Five multipliers are respectively connected to the outputs of the memories to multiply the pixel data with tap weight coefficients. The multiplied data are summed together to produce a single-line output signal for transmission. It is the current practice to implement the CIF converter using LSI technology.
Since a multiplier is made up of complex logic elements, it occupies a substantial amount of space in an LSI chip and dissipates a substantial amount of power. It has therefore been desired to reduce the number of multipliers required to implement a CIF converter.